You can’t see particle length from the tractor seat. You can see it in the cows. Sorting at the bunk, loose manure, cud chewing dropping off. A TMR particle size test with a shaker box takes ten minutes and tells you whether the mixer is doing its job.
What you need
A particle separator, often called a shaker box. It’s a set of stacked sieves with different hole sizes and a solid pan at the bottom. Most nutritionists and extension services have one, and they don’t cost much to buy.
How to run the test
- Sample fresh feed right after delivery, from several spots along the bunk. Mix those grabs together.
- Put a measured amount on the top sieve. Follow the guidance for your separator.
- Shake on a flat surface in the pattern the instructions give, usually a set number of horizontal shakes, rotating the box between sets.
- Weigh what’s on each sieve and the pan. Work out each as a percent of the total.
- Repeat a couple of times and average.
Reading the results
Compare against the targets your nutritionist sets for that ration. Different separators and rations have different targets, so don’t copy numbers from another farm.
Then test refusals too. If the leftovers are far longer than the fresh feed, the animals are sorting.
What to change when it’s off
Too much long material:
- Knives may be dull. Check them.
- Mix a bit longer after the last ingredient.
- Load hay first and give it time to process.
- Use restrictors to hold forage against the auger.
Too fine:
- You’re overmixing. Cut the time.
- Pull restrictors out once the hay is processed.
- Very sharp knives on dry hay can overprocess. Adjust timing.
Big difference between start and end of the bunk:
- The load isn’t mixed evenly. Check load order and mix time.
- Dead spots in the tub can be a cause.
Knives matter more than people think
Dull knives tear instead of cut, and you lose time and fuel. Our V2 modular knife system was built so swapping knives is quick, which means you’ll actually do it.
Understanding the sieves
Each sieve catches particles above a certain size. The top sieve catches the longest material, which keeps the rumen working and cows chewing their cud. The middle sieves catch medium particles. The pan catches fine material, which digests fast.
Too much on top and cows sort. Too much in the pan and rumen health can suffer. The balance depends on your ration and animals.
Testing along the bunk
Take samples at the start, middle and end of the bunk. Run each through the separator. If they’re different, the mix isn’t uniform. Look at load order, mix time and dead spots in the tub.
Testing over the day
Take a sample right after feeding and another a few hours later. If the later sample has more long material, cows are sorting out the shorter, tastier bits.
Keeping records
Write down the date, ration, mix time, knife condition and results. Over time, you’ll see patterns. Mix time creeping up with the same results? Knives are wearing. Results changing with no ration change? Something in the routine changed.
Common mistakes in testing
- Taking one sample from one spot.
- Shaking too hard or too soft.
- Not following the shaking pattern.
- Using wet hands that make feed stick.
- Comparing results from different separators.
Involving your nutritionist
Share results with your nutritionist. They can link changes in particle size to changes in milk, gain or manure. It makes the test far more useful.
How often to test
Test whenever the ration changes, when a new silage pile or bunker is opened, when knives are changed, and when a new operator starts. Outside of that, once a week or every two weeks is a sensible routine on most farms. It only takes a few minutes, and it’s one of the cheapest checks you can do on your feeding program.
Keep the separator clean and dry between tests, and store it out of the weather so the sieves don’t warp.
Make it routine
Test after every ration change, when forage changes, and once a month otherwise. Write it down. Over a season you’ll see exactly how your mixer and your crew are performing.
Learn more about LEO Agriculture and our full line of feed mixers and manure spreaders.
